1. Field of the Invention
The present invention relates to a radiation image sensor used for medical X-ray photography and the like.
2. Related Background Art
While X-ray sensitive films have been used in medical and industrial X-ray photography, radiation imaging systems using radiation detecting devices have been coming into wider use from the viewpoint of convenience and their storability of photographed results. In such a radiation imaging system, pixel data caused by two-dimensional radiation are acquired by a radiation detecting device as an electric signal, which is then processed by a processing unit, so as to be displayed onto a monitor.
Conventionally known as a typical radiation detecting device is one disclosed in WO92/06476. In this radiation detecting device, a scintillator formed on a substrate and an imaging device are bonded together with an adhesive, such that the radiation incident from the substrate side is converted into visible light by the scintillator, so as to be detected.
Meanwhile, individual columnar crystals of the scintillator formed on the substrate have different heights, thus yielding unevenness, whereby the tip portion of scintillator might collide with the light-receiving surface of imaging device when being bonded to the imaging device, thereby being damaged. Also, when the imaging device and the scintillator are firmly attached to each other with an adhesive, a distortion may occur in the substrate due to temperature changes, thereby causing a damage to columnar crystals of the scintillator. In the case where a cooling type CCD is used for the imaging device in particular, the distortion becomes greater upon drastic temperature changes, whereby the scintillator is more likely to be damaged.
It is an object of the present invention to provide a radiation image sensor which can prevent the scintillator from being damaged.
The present invention provides a radiation image sensor comprising a scintillator panel and an imaging device; wherein the scintillator panel comprises a radiation-transparent substrate, a scintillator formed on the substrate, and an elastic organic film covering the top and sides of the scintillator, and firmly attached to each other with a resin which surrounds the sides of the scintillator panel.
According to the present invention, since the scintillator is covered with an elastic organic film, the impact acting on the scintillator can be alleviated by way of the elastic organic film when bonding the scintillator panel to the imaging device, whereby the scintillator can be prevented from being damaged. Also, even when a distortion is generated in the substrate due to temperature changes, since the scintillator is covered with the elastic organic film, the stress acting on the scintillator according to the distortion of substrate can be alleviated by the elastic organic film, whereby the scintillator can be prevented from being damaged.
The resin may be attached to the side wall portions of the imaging device. It is preferable to fix the scintillator panel and the imaging device securely.
A radiation image sensor may further comprise an optical coupling material interposed between the scintillator panel and the imaging surface of the imaging device for improving imaging properties.
Also, the present invention is characterized in that the scintillator of radiation image sensor has a columnar structure. According to the present invention, since the tip portion of the scintillator having a columnar structure is covered with the elastic organic film, the impact acting on the tip portion of the scintillator having a columnar structure when superposing the scintillator panel onto the imaging device and the stress acting on the scintillator according to the distortion caused by temperature changes can be alleviated, whereby the tip portion of the scintillator having a columnar structure can be prevented from being damaged.
Preferably, the elastic organic film may cover the opposite side of the substrate on which the scintillator formed for securely protecting the scintillator from the moisture.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.